The present invention concerns a new nuclear power plant, more particularly for a light water power station. It also concerns a method of constructing such a power station.
The plant as a whole for a nuclear power station has to date been organized around a central building termed the "reactor building" containing the core of the reactor and the primary cooling circuit loops, and in particular the steam generators. In known plants, the reactor building is in the form of a very tall concrete structure, in the shape of a circular cylinder with vertical axis. The building containing the electric turbogenerators or engine room, the building for the fuel as well as the various ancillary buildings are then distributed all around the reactor building.
This conventional arrangement, which as far as use of the power station is concerned, is generally satisfactory, does, however, present the disadvantage of causing considerable delays in construction. In practice, the construction of a conventional power station of the light water type and in particular the complete erection of the reactor building at present involves two stages.
The first stage is that of constructing the building, properly so-called, or the civil engineering phase of execution. It involves constructing a concrete foundation on which the various concrete elements are mounted, such as the biological shields, the protective chambers for the steam generators, etc. At the upper part of the vessel, a revolving bridge is then mounted which will be used first for putting heavy equipment in position and then, during use, for various handling operations.
The second stage is that of putting heavy equipment in position, which can only be done after completion of the first stage. In practice the cleanness required for the pieces of equipment constituting the circulation loops of the primary fluid between the reactor-core and the steam generators makes it impossible to carry out heavy civil engineering work in their vicinity. Furthermore, it is at present necessary for the revolving bridge to be in position at the upper part of the enclosure so that the heavy units, such as the reactor vessel, the pressurizer or the steam generators can be put in position. An additional fact is that access to the site of the reactor building is made difficult by the presence all around the construction sites of attached buildings. It will also be noted that maneuvering at the bridge of the steam generators, which have been brought into the building at the level of the working floor, necessitates setting them upright again and then raising them by a height which is sufficient to bring them to the vertical on their supports in the protective chambers before they are left in position there. This makes it necessary to have considerable height under the bridge and consequently for the reactor building to have a considerable height, which increases its cost and its sensitivity to earthquakes and makes it essential to increase its strength.